Packers coach Mike McCarthy was noncommital on Aaron Rodgers' injury late Monday night. "They don’t have an exact diagnosis," he said. "That’s where we are."

His players, either by virtue of having more information or of being more open with the news, sounded the alarm more directly. WR Jordy Nelson spoke of how Rodgers' last injury, in 2010, "wasn’t as long as this possibly could be." RB Eddie Lacy talked about the importance of an improved run game going forward in Rodgers' absence.

Had Green Bay held off Chicago, perhaps there would be less mounting panic. The 27-20 setback, however, dropped the Packers to 5-3, in a three-way tie with the Bears and Lions for first place in the NFC North. The upcoming schedule is favorable for Green Bay: home vs. Philadelphia, at the Giants and home vs. Minnesota, before a Thanksgiving Day showdown in Detroit.

"I don’t think it’s realistic to put anybody in there and think they’re going to pick up and run it the way he has run it," said McCarthy of his offense sans Rodgers. "But it’s our job as coaches to make sure that Seneca is comfortable and put him into positions, put him into concepts that we can execute and be successful in."

Wallace made an underwhelming initial impression Monday, throwing an interception and struggling to move the offense through the air. As McCarthy pointed out, though, Wallace sees as few first-team practice reps as possibly any quarterback in the league. The Packers count on Rodgers being on the field every week; they know they are in serious trouble if he is not.

As with any situation in which a backup is forced into duty, his play should improve as he has more time to work with the starting offense. Wallace, then, should at least be closer to his comfort zone next Sunday against a beatable Philadelphia defense.

Will that be enough?

"We’ve got to have confidence and know we can move the ball, and do the things we need to do regardless of who’s playing quarterback," Wallace said. "[My teammates] looked at me and said ‘Let’s go,’ and I know I’ve got to go there and perform at a high level for them."

He was unable to do that against Chicago, and had it not been for some big runs from Eddie Lacy and James Starks, the Packers may not have even been in the mix late.

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Rodgers' injury also comes just as the Bears expect Jay Cutler to return from his own ailment, and as the Lions' schedule lightens up. Cutler is expected to suit up against Detroit in Week 10 -- that and Thanksgiving against Green Bay are the only times Detroit plays a team at .500 or better from here out.

Green Bay's hope is that Wallace can manage the game well enough to prevent a massive drop-off in Rodgers' absence. Realistically, with other players like Jermichael Finley, Randall Cobb and others still out of the lineup, simply keeping pace in the NFC North will be a tough enough task.

"I think we’ll be fine," Nelson said. "We trust Seneca. He has a proven track record and he’s been around the league long enough. We have all the faith in the world in him. ... It’s just another opportunity for someone else in this locker room to step up."

That the Packers, battered by those injuries, were 5-2 in the first place was a testament to Rodgers' abilities. What happened in his absence Monday night may be a troubling omen of what's to come.

Green Bay still has plenty to play for -- and the talent to keep this train on the tracks. But replacing Rodgers for an extended period of time drops a taller hurdle in front of this team than it has seen in a long time.